Study of Mutations in katG and inhA Genes by High Resolution Method in Isoniazid Resistant Mycobacterium tuberculosis Isolates

Tuberculosis is one of the infectious diseases worldwide that has resurgence by the AIDS epidemic and led to the rise of drug-resistant tuberculosis patients. Thus, it seems essential to monitor the drug susceptibility in tuberculosis patients. The new High Resolution Melting (HRM) method is simple, rapid and inexpensive for detection of the mutations responsible for drug resistance in Mycobacterium tuberculosis isolates. In this study, we used HRM method to detect mutations in samples collected from tuberculosis patients.
Three thousand sputum samples were collected from patients with suspected tuberculosis referred to Iran Remedial Center over a period of 2 years, out of which 2000 samples were found positive for M. Tuberculosis on direct smear. After extraction of genomic DNA from sputums, HRM method was used to detection of mutations in katG and inhA genes.
Our findings showed that 120 out of 2000 positive smear samples were resistant to isoniazid due to mutations in katG and inhA genes, out of which, 25 mutation was found in inhA gene and 95 mutation in katG gene.
The HRM method is quick, easy and affordable without need of culture and any post PCR process for diagnosing of drug resistance in tuberculosis clinical samples.